Hydraulic well control system

ABSTRACT

A system for transmitting hydraulic control signals and hydraulic power to downhole well tools while reducing the number of hydraulic lines installed in the wellbore. Hydraulic control signals can be furnished at relatively lower pressures, and the hydraulic pressure within the line can be selectively increased over a threshold level to provide hydraulic actuation power. The system can provide multiple control paths through a few number of hydraulic lines to provide flexibility and verification of well tool operation. Closed loop hydraulic operation monitors well tool operation, and a combination of pressurized hydraulic lines can provide an operating code for selective downhole well tool control. Four hydraulic lines can provide independent control and actuation of seven well tools, and additional combinations can be constructed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. national stage filing of PCTapplication no. PCT/GB99/02694, filed Aug. 13, 1999, which is a filingunder the Patent Cooperation Treaty of prior U.S. application Ser. No.09/133,747, filed Aug. 13, 1998, now U.S. Pat. No. 6,179,052, and whichis related to copending U.S. application Ser. No. 09/510,701, filed Feb.22, 2000. The disclosures of the above applications are incorporatedherein by this reference.

BACKGROUND OF THE INVENTION

The present invention relates to a system for controlling the productionof hydrocarbons and other fluids from downhole wells. More particularly,the invention relates to a system for providing hydraulic controlsignals and power through the same hydraulic line, and for providingintegrated control of multiple well tools with a minimal number ofhydraulic lines.

Various tools and tool systems have been developed to control, select orregulate the production of hydrocarbon fluids and other fluids produceddownhole from subterranean wells. Downhole well tools such as slidingsleeves, sliding side doors, interval control lines, safety valves,lubricator valves, and gas lift valves are representative examples ofcontrol tools positioned downhole in wells.

Sliding sleeves and similar devices can be placed in isolated sectionsof the wellbore to control fluid flow from such wellbore section.Multiple sliding sleeves and interval control valves (ICVs) can beplaced in different isolated sections within production tubing tojointly control fluid flow within the particular production tubingsection, and to commingle the various fluids within the commonproduction tubing interior This production method is known as“comingling” or “coproduction”. Reverse circulation of fluids throughthe production of tubing, known as “injection splitting”, is performedby pumping a production chemical or other fluid downwardly into theproduction tubing and through different production tubing sections.

Wellbore tool actuators generally comprise short term or long termdevices. Short term devices include one shot tools and tool havinglimited operating cycles. Long term devices can use hydraulicallyoperated mechanical mechanisms performing over multiple cycles.Actuation signals are provided through is mechanical, direct pressure,pressure pulsing, electrical, electromagnetic, acoustic, and othermechanisms. The control mechanism may involve simple mechanics, fluidlogic controls, timers, or electronics. Motive power to actuated thetools can be provided through springs, differential pressure,hydrostatic pressure, or locally generated power.

Long term devices provide virtually unlimited operating cycles and aredesigned for operation through the well producing life. One long termsafety valve device provides fail safe operating capabilities whichcloses the tubing interior with spring powered force when the hydraulicline pressure is lost. Combination electrical and hydraulic poweredsystems have been developed for downhole use, and other systems includesensors which verify proper operation of tool components.

Interval control valve (ICV) activation is typically accomplished withmechanical techniques such as a shifting tool deployed from the wellsurface on a workstring or coiled tubing. This technique is expensiveand inefficient because the surface controlled rigs may be unavailable,advance logistical planning is required, and hydrocarbon production islost during operation of the shifting tool. Alternatively, electricaland hydraulic umbilical lines have been used to remotely control one ormore ICVs without reentry to the wellbore.

Control for one downhole tool can be hydraulically accomplished byconnecting a single hydraulic line to a tool such as an ICV or alubricator valve, and by discharging hydraulic fluid from the line endinto the wellbore. This technique has several limitations as thehydraulic fluid exits the wellbore because of differential pressuresbetween the hydraulic line and the wellbore. Additionally, the settingdepths are limited by the maximum pressure that a pressure relief valvecan hold between the differential pressure between the control linepressure and the production tubing when the system is at rest. Theselimitations restrict single line hydraulics to low differential pressureapplications such a lubricator valves and ESP sliding sleeves. Further,discharge of hydraulic fluid into the wellbore comprises anenvironmental discharge and risks backflow and particulate contaminationinto the hydraulic system. To avoid such contamination and corrosionproblems, closed loop hydraulic systems are preferred over hydraulicfluid discharge valves downstream of the well tool actuator.

Certain techniques have proposed multiple tool operation through asingle hydraulic line. U.S. Pat. No 4,660,647 to Richart (1987)disclosed a system for changing downhole flow paths by providingdifferent plug assemblies suitable for insertion within a side pocketmandrel downhole in the wellbore. In U.S. Pat. No. 4,796,699 to Upchurch(1989), an electronic downhole controller received pulsed signals forfurther operation of multiple well tools. In U.S. Pat. No. 4,942,926 toLessi (1990), hydraulic fluid pressure from a single line was directedby solenoid valves to control different operations. A return means inthe form of a spring facilitated return of the components to theoriginal position. A second hydraulic line was added to provide for dualoperation of the same tool function by controlling hydraulic fluid flowin different directions. Similarly, U.S. Pat. No. 4,945,995 to Thulanceet al. (1990) disclosed an electrically operated solenoid valve forselectively controlling operation of a hydraulic line for openingdownhole wellbore valves.

Other downhole well tools use two hydraulic lines to control a singletool. In U.S. Pat. No. 3,906,726 to Jameson (1975), a manual controldisable valve and a manual choke control valve control the flow ofhydraulic fluid on either side of a piston head. In U.S. Pat. No.4,197,879 to Young (1980), and in U.S. Pat. No. 4,368,871 to Young(1983), two hydraulic hoses controlled from a vessel were selectivelypressurized to open and close a lubricator valve during well testoperations. A separate control fluid was directed by each hydraulic hoseso that one fluid pressure opened the valve and a different fluidpressure closed the valve. In U.S. Pat. No. 4,476,933 to Brooks (1984),a piston shoulder functioned as a double acting piston in a lubricatorvalve, and two separate control lines were connected to conduits and toconventional fittings to provide high or low pressures in chambers onopposite sides of the piston shoulder. In U.S. Pat. No. 4,522,370 toNoack et al. (1985), a combined lubricator and retainer valve wasoperable with first and second pressure fluids and pressure responsivemembers, and two control lines provided two hydraulic fluid pressures tothe control valve. This technique is inefficient because two hydrauliclines are required for each downhole tool, which magnifies the problemsassociated with hydraulic lines run through packers and wellheads.

Instead of multiple hydraulic lines, other techniques have attempted toestablish an operating sequence. In U.S. Pat. No. 5,065,825 to Bardin etal. (1991), a solenoid valve was operated in response to a predeterminedsequence to move fluid from one position to another. A check valvepermitted discharge of oil into a reservoir to replenish the reservoiroil pressure. Other systems use electronic controllers downhole in thewellbore to distribute, however the electronics are susceptible totemperature induced deterioration and other reliability problems.

Multiple hydraulic lines downhole in a wellbore can extend for thousandsof feet into the wellbore. In large wellbores having differentproduction zones and multiple tool requirements, large numbers ofhydraulic lines are required. Each line significantly increasesinstallation cost and the number of components potentially subject tofailure. Accordingly, a need exists for an improved well control systemcapable of avoiding the limitations of prior art devices. The systemshould be reliable, should be adaptable to different tool configurationsand combinations, and should be inexpensive to deploy.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and system for transmittingpressurized fluid between a wellbore surface and a well tool locateddownhole in the wellbore. The apparatus comprises at least two hydrauliclines engaged with the well tool for conveying said fluid to the welltool, and means for pressurizing the fluid within the hydraulic lines.The hydraulic lines are capable of providing communication controlsignals to the well tool are further capable of providing fluid pressureto actuate the well tool. In different embodiments of the invention, atleast three hydraulic lines are each engaged with each well tool forselectively conveying the fluid to each well tool, and hydraulic controlmeans engaged between said hydraulic lines and each well tool forselectively controlling actuation of each well tool in response topressure changes within selected hydraulic lines.

The invention also provides a system for controlling at least three welltools located downhole in a wellbore. The system comprises hydraulicpressure means for selectively pressurizing a fluid, at least twohydraulic lines engaged with the hydraulic pressure means and with eachwell tool for selectively conveying fluid pressure to each well tool,and hydraulic control means engaged between each hydraulic line and eachwell tool. Each hydraulic control means is operable in response toselective pressurization of one or lore hydraulic lines by saidhydraulic pressure means, and operation of a well tool through thepressurization of one hydraulic line displaces fluid which is conveyedthrough another hydraulic line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a two hydraulic line system for providing hydraulicpressure control and power to well tools.

FIG. 2 illustrates a graph showing a hydraulic line pressure code forproviding hydraulic control and power capabilities through the samehydraulic line.

FIG. 3 illustrates a three well tool and three hydraulic line apparatus.

FIG. 4 shows a representative control code for the apparatus shown inFIG. 3.

FIG. 5 illustrates a seven well tool and four hydraulic line system forproviding selective well control and power.

FIG. 6 illustrates a representative control code for the system shown inFIG. 5.

FIG. 7 illustrates another seven well tool and four hydraulic linesystem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention provides hydraulic fluid control for downhole well toolsby uniquely utilizing hydraulics with logic circuitry. Such logiccircuitry is analogous to electrical and electronics systems, anddepends on Boolean logic using “AND” and “OR” gates in the form ofhydraulic switches. Using this unique concept, digital controlcapability, or “digital-hydraulics” can be adapted to the control ofdownhole well tools such as ICVs.

FIG. 1 illustrates two hydraulic lines 10 and 12 engaged with pump 14for providing hydraulic pressure to fluid (not shown) in lines 10 and12. Lines 10 and 12 are further engaged with downhole well tools 16 and18 for providing hydraulic fluid pressure to tools 16 and 18. Pump 14can comprise a controller for selectively controlling the fluid pressurewithin lines 10 and 12, and can cooperate with a hydraulic control meanssuch as valve 20 located downhole in the wellbore in engagement withlines 10 and 12, and with tools 16 and 18. Selectively control over thedistribution of hydraulic fluid pressure can be furnished and controlledwith pump 14 at the wellbore surface, or with valve 20 downhole in thewellbore. Control signals to tools 16 and 18 and valve 20 can beprovided within a different pressure range as that required foractuation of tools 16 and 18, and the ranges can be higher, lower, oroverlapping.

FIG. 2 illustrates one combination of communication and power functionsthrough the same hydraulic tubing, conduit, passage or line such as line10 wherein the control signals are provided at lower pressures than thepower actuation pressures. Pressure is plotted against time, and thehydraulic pressure is initially raised above the communication thresholdbut below the power threshold. Within this pressure range, communicationsignals and controls can be performed through the hydraulic line. Theline pressure is raised to a selected level so that subsequent poweringup of the hydraulic line pressure raises the line pressure to a certainlevel. Subsequent actuation of the well control devices, normallydelayed as the pressure builds up within the long hydraulic tubing,occurs at a faster rate because the line is already pressurized to acertain level.

The invention further permits the use of additional hydraulic lines andcombinations of hydraulic lines and controllers to provide ahydraulically actuated well control and power system. One embodiment ofthe invention is based on the concept that a selected number ofhydraulic control lines could be engaged with a tool and that controlline combinations can be used for different purposes. For example, athree control line system could use a first line for hydraulic powersuch as moving a hydraulic cylinder, a second line to provide a returnpath for returning fluid to the initial location, and all three linesfor providing digital-hydraulic code capabilities. Such code can berepresented by the following Table:

Hydraulic Lines #1 #2 #3 Digital Equation Numeric Value Lines 0 0 0 0 ×2² + 0 × 2¹ + 0 × 2⁰ = 0 0 0 1 0 × 2² + 0 × 2¹ + 1 × 2⁰ = 1 0 1 0 0 ×2² + 1 × 2¹ + 0 × 2⁰ = 2 0 1 1 0 × 2² + 1 × 2¹ + 1 × 2⁰ = 3 1 0 0 1 ×2² + 0 × 2¹ + 0 × 2⁰ = 4 1 0 1 1 × 2² + 0 × 2¹ + 1 × 2⁰ = 5 1 1 0 1 ×2² + 1 × 2¹ + 0 × 2⁰ = 6 1 1 1 1 × 2² + 1 × 2¹ + 1 × 2⁰ = 7

If “1” represents a pressurized line and if “0” represents anunpressurized line, then the combination of hydraulic lines provides thedescribed code format for a binary communication code. Because thehydraulic line operation can use both a pressurized and an unpressurizedline in a preferred embodiment of the invention, codes 000 and 111 wouldnot be used in this embodiment. However, if one or more lines dischargedfluid to the outside of the line to the tubing exterior, another tool,or other location, codes 000 and 111 would be useful for transmittingpower or signals. If codes 000 and 111 are excluded from use in theinventive embodiment described, the following six codes are availablefor tool control:

#1 #2 #3 0 0 1 — 1 0 1 0 — 2 0 1 1 — 3 1 0 0 — 4 1 0 1 — 5 1 1 0 — 6

These codes are unique and can be grouped to provide six independentdegrees of freedom to a hydraulic network. Different combinations arepossible, and one combination permits the operation of three well toolssuch as ICVs 22, 24, and 26 leaving double actuated floating pistons asillustrated in FIG. 3. Lines 28, 30 and 32 are engaged between pump 14and ICVs 22, 24, and 26. Lines 28, 30, and 32 could provide an openingcode 001 for ICV 22. After a sufficient time lapse for all well toolssuch as the ICVs has occured to detect and register the 001 code, theline pressure can be raised above the power threshold until a selectedpressure level is achieved. The pressure can be held constant at suchlevel, or varied to accomplish other functions. The selected well toolsuch as ICV 22 is actuated, and return fluid is directed back throughone or more of the lines designated as a “0”, unpressurized line. Next,control line 32 is bled to zero and the entire system is at rest,leaving ICV 22 fully open until further operation. To open ICV 24,control linesw 28, 30, and 32 can be coded and operated as illustrated.After sufficient time has passed, the system pressure call be increasedto operate ICV 24. The degrees of control freedom and operating controlscan be represented by the following instructions:

Hydraulic Line Number 28 30 32 0 0 1 Open ICV 22 0 1 0 Close ICV 22 0 11 Open ICV 24 1 0 0 Close ICV 24 1 0 1 Open ICV 26 1 1 0 Close ICV 26

${X = \frac{2^{N} - 2}{2}},\quad {{{and}\quad X} = {\frac{2^{3} - 2}{2} = 3}}$

control lines where

X equals the number of independently controlled ICVs, and

N equals the number of control lines.

Another combination is expressed below wherein additional ICVs 34 and 36are added to build a five well tool system.

Hydraulic Line Number 28 30 32 0 0 1 All ICVs Open 0 1 0 Close ICV 22 01 1 Close ICV 24 1 0 0 Close ICV 26 1 0 1 Close ICV 34 1 1 0 Close ICV36

Z=2″−3, and Z=2′—3=5 control lines where

Z equals the number of dependently controlled ICVs, and

N equals the number of control lines.

The number of independently and dependently controlled ICVs providessystem flexibility in the design of an operating system. For example,

#of Independent ICVs # of Control Lines N $X = \frac{2^{''} - 2}{2}$

#of Dependent ICVs Z = 2″ − 3 1 0 0 2 1 1 3 3 5 4 7 13 5 15 27 6 31 61 763 125 8 127 253

From this chart, the feasibility of the concept for one or two hydrauliclines does not offer significant control flexibility over single,dedicated hydraulic lines. At three control lines and greater, thebenefits of the digital-hydraulic system become apparent as significantcombinations of well control functions are available. For the majorityof conventional downhole well uses, four control lines are adequate.However, the concepts taught by the invention provide additionallydesign flexibility to accommodate additional requirements as indicated.

A four ICV digital-hydraulic control system having seven independentdevices and thirteen dependant devices can operate as follows:

Hydraulic Line Number #1 #2 #3 #4 Independent Dependent 0 0 0 1 OpenICV#1 All ICVs open 0 0 1 0 Close ICV#1 Close ICV#1 0 0 1 1 Open ICV#2Close ICV#2 0 1 0 0 Close ICV#2 Close ICV#3 0 1 0 1 Open ICV#3 CloseICV#4 0 1 1 0 Close ICV#3 Close ICV#5 0 1 1 1 Open ICV#4 Close ICV#6 1 00 0 Close ICV#4 Close ICV#7 1 0 0 1 Open ICV#5 Close ICV#8 1 0 1 0 CloseICV#5 Close ICV#9 1 0 1 1 Open ICV#6 Close ICV#10 1 1 0 0 Close ICV#6Close ICV#11 1 1 0 1 Open ICV#7 Close ICV#12 1 1 1 0 Close ICV#7 CloseICV#13

A representative embodiment of a four hydraulic line system isillustrated in FIG. 5 wherein hydraulic lines 40, 42, 44 and 46 areengaged with controller 48, and are further engaged with hydrauliccontrol means such as module 50 connected to tool 52, module 54connected to tool 56, module 58 connected to tool 60, module 62connected to tool 64, module 66 connected to tool 68, module 70connected to tool 72, and module 74 connected to tool 76. Selectivepressurization of lines 40, 42, 44 and 46 selectively operates one ormore of such seven well tools according to a programmed code asrepresented in FIG. 6. For example, a code of “0010”, wherein all linesare unpressurized except for the pressurization of line 44, operates toclose tool 52 as illustrated.

Each hydraulic control means or control mechanism can be designed with acombination of valves and other components to perform a desiredfunction. Referring to FIG. 3, control mechanism 78 includes two controlmodules 80 and 82 each located on opposite sides of the floating pistonwithin ICV 22. Control module 80 includes check valve engaged with line32, and further includes check valve 84 engaged with pilot operatedvalves 86 and 88. Pilot operated valve 86 is engaged with line 30, andpilot operated valve 88 is engaged with line 28. Check valves 90 and 92and pilot operated valves 94 and 96 are positioned as shown in FIG. 3for control module 82. Similar combinations of modules and internalcomponents are illustrated in FIG. 5 and in FIG. 7 for differentoperating characteristics.

The unique combination of valves and other components within eachcontrol module provides for unique, selected operating functions andcharacteristics. Depending on the proper sequence and configuration,pressurization of a hydraulic line can actuate one of the tools withoutactuating other tools in the system. Alternatively, various combinationsof well tools could be actuated with the same hydraulic line if desired.

By providing communication and power capabilities, through the samehydraulic lines, the invention significantly eliminates problemsassociated with pressure transients. In deep wellbores, the hydrauliclines are very long and slender, which greatly affects the hydraulicline ability to quickly transmit pressure pulses or changes from thewellbore surface to a downhole tool location. In deep wellbores, five toten minutes could be required before the hydraulic lines were accuratelycoded for the communication of sequenced controls. If some of the ICVswere located relatively shallow in the wellbore, such ICVs would receivethe code long before other ICVs located deep in the wellbore. Thisconfiguration could cause confusion on the digital-hyraulics controlcircuit.

This problem can be resolved by dedicating certain lines forcommunication signals and other lines for power. Alternatively, apreferred embodiment of the invention utilizes such time delaycharacteristics by applying the communication coding early at relativelylow pressures where the ICVs receive the codes but are not activated,and then the pressure is increased above a selected activation thresholdto move the ICVs. This permits communication and power to be transmittedthrough the same hydraulic lines, and further uses the communicationpressures to initially raise the line pressures to a selected level andto shorten the power up time required.

For another instruction, pistons within an ICV can be moved in adirection from the initial position toward a second position, and can bemaintained above second position pressure. The device response initiallydirects the control line pressure to the second side of the pistonactuator. As the piston responds to the force created by thedifferential pressure, fluid on the low pressure side is displaced intothe tubing. The device eventually strokes fully and attains the secondposition, and the fluid will slowly bleed away.

Another embodiment of the invention is illustrated below where certainlines are dedicated as power lines and other lines are dedicated ascommunication control lines. A representative sequence code for a fiveLine tool system can be expressed as follows:

Communication Power Lines Lines #1 #2 A B C Independent Dependent 0 1 00 0 Open ICV#1 All ICVs closed 1 0 0 0 0 Close ICV#1 Open ICV#1 0 1 0 01 Open ICV#2 Open ICV#2 1 0 0 0 1 Close ICV#2 Open ICV#3 0 1 0 1 0 OpenICV#3 Open ICV#4 1 0 0 1 0 Close ICV#3 Open ICV#5 0 1 0 1 1 Open ICV#4Open ICV#6 1 0 0 1 1 Close ICV#4 Open ICV#7 0 1 1 0 0 Open ICV#5 OpenICV#8 1 0 1 0 0 Close ICV#5 Open ICV#9 0 1 1 0 1 Open ICV#6 Open ICV#101 0 1 0 1 Close ICV#6 Open ICV#11 0 1 1 1 0 Open ICV#7 Open ICV#12 1 0 11 0 Close ICV#7 Open ICV#13 0 1 1 1 1 Open ICV#8 Open ICV#14 1 0 1 1 1Close ICV#8 Open ICV#15 5 Lines, 8 ICVs 5 Lines, 15 ICVs

Although more lines are required to control a certain number of welltools, this embodiment of the invention provides certain designbenefits. Response time within the lines can be faster, a singlepressure level can be utilized, and any possibility of confusion betweena communication pressure code and a power pressure code is eliminated.

The invention is applicable to many different tools including downholedevices having more than one operating mode or position from a singlededicated hydraulic line. Such tools include tubing mounted ball valves,sliding sleeves, lubricator valves, and other devices. The invention isparticularly suitable for devices having a two-way piston, open/closeactuator for providing force in either direction in response todifferential pressure across the piston.

The operating codes described above can be designed to provide a staticoperating code where the fluid pressures stabilize within each hydraulicline. By providing for static pressures at different levels,communication control signals can be provided by the presence or absenceof fluid pressure, or by the fluid pressure level observed. For example,different pressure levels through one or more lines can generatedifferent system combinations far in excess of the “0” and “1”combinations stated above, and can provide for multiple combinations atleast three or four time greater. In effect, a higher order ofcombinations is possible by using different line pressures incombination with different hydraulic lines. Alternatively, the operationof a single line can be pulsed in cooperation with a well tool or ahydraulic control means operation, or can be pulsed in combination withtwo or more hydraulic lines to achieve additional control sequences.Such pulsing techniques further increase the number of systemcombinations available through a relatively few number of hydrauliclines, thereby providing maximum system capabilities with a minimumnumber of hydraulic lines.

Although the preferred embodiment of the invention permits hydraulicswitching of the lines for operation of downhole well tools such asICVs, switching functions could be performed with various switchtechniques including electrical, electromechanical, acoustic,mechanical, and other forms of switches. The digital hydraulic logicdescribed by the invention is applicable to different combinations ofconventional and unconventional switches and tools, and provides thebenefit of significantly increasing system reliability and of permittinga reduction in the number of hydraulic lines run downhole in thewellbore.

The invention permits operating forces in the range above 10,000 lb. andis capable of driving devices in different directions. Such high drivingforces provide for reliable operation where environmental conditionscausing scale and corrosion increase frictional forces over time. Suchhigh driving forces also provide for lower pressure communication rangessuitable for providing various control operations and sequences.

The invention controls a large number of downhole well tools whileminimizing the number of control lines extending between the tools andthe wellbore surface. A subsurface safety barrier is provided to reducethe number of undesirable returns through the hydraulic lines, and highactivation forces are provided in dual directions. The system isexpandable to support additional high resolution devices, can supportfail safe equipment, and can provide single command control or multiplecontrol commands. The invention is operable with pressure or no pressureconditions, can operate as a closed loop or open loop system, and isadaptable to conventional control panel operations. A an open loopsystem, hydraulic fluid can be exhausted from one or more lines or welltools if return of the hydraulic fluid is not necessary to the wellboreapplication. The invention can further be run in parallel with otherdownhole wellbore power and control systems. Accordingly, the inventionis particularly useful in wellbores having multiple zones or connectedbranch wellbores such as in multilateral wellbores.

Although the invention has been described in terms of certain preferredembodiments it will become apparent to those of ordinary skill in theart that modifications and improvements can be made to the inventiveconcepts herein without departing from the scope of the invention. Theembodiments shown herein are merely illustrative of the inventiveconcepts and should not be interpreted as limiting the scope of theinvention.

What is claimed is:
 1. An apparatus for transmitting pressurized fluidbetween a wellbore surface and a well tool located downhole in thewellbore, comprising: at least two hydraulic lines engaged with the welltool for conveying the fluid to the well tool, wherein the hydrauliclines are capable of providing communication control signals to the welltool, and wherein the hydraulic lines are further capable of providingfluid pressure to actuate the well tool, at least one of the hydrauliclines used to provide fluid pressure to actuate the well tool being thesame as at least one of the hydraulic lines used to providecommunication control signals to the well tool; and a fluid pressurizercoupled with the hydraulic lines to provide the communication signalsand the fluid actuation pressure.
 2. The apparatus as recited in claim1, further comprising a controller for selectively pressurizing thehydraulic lines.
 3. The apparatus as recited in claim 1 wherein thecommunication control signals are provided in a static code identifiedby the presence of a selected fluid pressure.
 4. The apparatus asrecited in claim 1, wherein the hydraulic lines are capable of providingwell tool actuation pressure, after communication control signals aretransmitted to the well tool, by increasing the fluid pressure in atleast one hydraulic line.
 5. The apparatus as recited in claim 1,wherein the hydraulic lines form a closed loop for returning fluid tothe wellbore surface, further comprising means for detecting the returnof fluid through one hydraulic line when another hydraulic line ispressurized.
 6. An apparatus for transmitting pressurized fluid betweena wellbore surface and a well tool located downhole in the wellbore,comprising: at least two hydraulic lines engaged with the well tool forconveying the fluid to the well tool, wherein the hydraulic lines arecapable of providing communication control signals to the well tool, andwherein the hydraulic lines are further capable of providing fluidpressure to actuate the well tool; and a fluid pressurizer coupled withthe hydraulic lines to provide the communication signals and the fluidactuation pressure, the communication control signals comprising a lowerpressure than the fluid pressure for actuating the well tool.
 7. Anapparatus for transmitting pressurized fluid between a wellbore surfaceand a well tool located downhole in the wellbore, comprising: at leasttwo hydraulic lines engaged with the well tool for conveying the fluidto the well tool, wherein the hydraulic lines are capable of providingcommunication control signals to the well tool, and wherein thehydraulic lines are further capable of providing fluid pressure toactuate the well tool; and a fluid pressurizer coupled with thehydraulic lines to provide the communication signals and the fluidactuation pressure, the communication control signals being provided ina pulsed sequence.
 8. An apparatus for transmitting pressurized fluidbetween a wellbore surface and a well tool located downhole in thewellbore, comprising: at least two hydraulic lines engaged with the welltool for conveying the fluid to the well tool, wherein the hydrauliclines are capable of providing communication control signals to the welltool, and wherein the hydraulic lines are further capable of providingfluid pressure to actuate the well tool; and a fluid pressurizer coupledwith the hydraulic lines to provide the communication signals and thefluid actuation pressure, at least three well tools being each engagedwith said two or more hydraulic lines, the apparatus further comprisinga switch engaged with the hydraulic lines and the well tools foractuating one of the well tools by the selective pressurization of onehydraulic line.
 9. An apparatus for transmitting pressurized fluidbetween a wellbore surface and a well tool located downhole in thewellbore, comprising: at least two hydraulic lines engaged with the welltool for conveying the fluid to the well tool, wherein the hydrauliclines are capable of providing communication control signals to the welltool, and wherein the hydraulic lines are further capable of providingfluid pressure to actuate the well tool; and a fluid pressurizer coupledwith the hydraulic lines to provide the communication signals and thefluid actuation pressure, at least three well tools being each engagedwith the two or more hydraulic lines, the apparatus further comprising aswitch engaged with the hydraulic lines and the well tools for actuatingone of the well tools by the selective pressurization of two hydrauliclines.
 10. An apparatus for transmitting pressurized fluid between awellbore surface and a well tool located downhole in the wellbore,comprising: at least two hydraulic lines engaged with the well tool forconveying the fluid to the well tool, wherein the hydraulic lines arecapable of providing communication control signals to the well tool, andwherein the hydraulic lines are further capable of providing fluidpressure to actuate the well tool; and a fluid pressurizer coupled withthe hydraulic lines to provide the communication signals and the fluidactuation pressure, one of the lines being dedicated to providecommunication control signals.
 11. An apparatus for transmittingpressurized fluid between a wellbore surface and a well tool locateddownhole in the wellbore, comprising: at least two hydraulic linesengaged with the well tool for conveying the fluid to the well tool,wherein the hydraulic lines are capable of providing communicationcontrol signals to the well tool,,and wherein the hydraulic lines arefurther capable of providing fluid pressure to actuate the well tool;and a fluid pressurizer coupled with the hydraulic lines to provide thecommunication signals and the fluid actuation pressure, one of the linesbeing dedicated to provide fluid pressure to actuate the well tool. 12.An apparatus for transmitting pressurized fluid between a wellboresurface and three well tools located downhole in the wellbore,comprising: at least three hydraulic lines each engaged with each welltool for selectively conveying the fluid to each well tool; and acontroller engaged between the hydraulic lines and each well tool forselectively controlling actuation of each well tool in response topressure changes within selected hydraulic lines.
 13. The apparatus asrecited in claim 12, wherein the controller comprises a hydrauliccontrol means responsive to operation when contacted by changes in thepressure of the pressurized fluid.
 14. The apparatus as recited in claim12, wherein the well tools are actuatable in two directions fromopposing positions of each well tool, and wherein the controllercomprises two control modules separately engaged with the opposing welltool positions so that each control module is capable of providingselective fluid flow in two directions relative to the well tool. 15.The apparatus as recited in claim 14, wherein each control modulecomprises a hydraulic circuit having a check valve for resisting fluidflow from the tool direction and in communication with one of saidhydraulic lines, and further comprises a pilot operated valve engagedwith the hydraulic line and with the tool which is closed in an initialcondition and is actuatable by a fluid pressure increase in one of theother hydraulic lines.
 16. The apparatus as recited in claim 15, furthercomprising another pilot operated valve engaged with the hydraulic lineand with the tool which is closed in an initial condition and isactuatable by a fluid pressure increase in the third of said hydrauliclines.
 17. The apparatus as recited in claim 16, further comprising acheck valve engaged in series with the pilot operated valve between thehydraulic line and the tool.
 18. The apparatus as recited in claim 12,wherein the hydraulic lines are further capable of providing fluidpressure to actuate the well tool.
 19. A system for controlling at leastthree well tools located downhole in a wellbore, comprising: a hydraulicpressurizer located at the wellbore surface for selectively pressurizinga fluid; at least two hydraulic lines engaged with the hydraulicpressurizer and with each well tool for selectively conveying fluidpressure to each well tool; and a hydraulic controller engaged betweeneach hydraulic line and each well tool, wherein each hydrauliccontroller is operable in response to selective pressurization of one ormore hydraulic lines by the hydraulic pressurizer, and wherein operationof a well tool through the pressurization of one hydraulic linedisplaces fluid which is conveyed through another hydraulic line, atleast one of the hydraulic lines used to provide fluid pressure toactuate one of the at least three well tools being the same as at leastone of the hydraulic lines used to operate the hydraulic controllerassociated with the one of the at least three well tools.
 20. The systemas recited in claim 19, further comprising a fluid, controller fordetecting the displaced fluid conveyed through a hydraulic line duringoperation of a well tool.
 21. A system for controlling at least threewell tools located downhole in a wellbore, comprising: a hydraulicpressurizer for selectively pressurizing a fluid; at least two hydrauliclines engaged with the hydraulic pressurizer and with each well tool forselectively conveying fluid pressure to each well tool; a hydrauliccontroller engaged between each hydraulic line and each well tool,wherein each hydraulic controller is operable in response to selectivepressurization of one or more hydraulic lines by the hydraulicpressurizer, and wherein operation of a well tool through thepressurization of one hydraulic line displaces fluid which is conveyedthrough another hydraulic line; and a fluid controller for detecting thedisplaced fluid conveyed through a hydraulic line during operation of awell tool, wherein the fluid controller is capable of measuring thedisplaced fluid conveyed through the hydraulic line.
 22. A system forcontrolling at least three well tools located downhole in a wellbore,comprising: a hydraulic pressurizer for selectively pressurizing afluid; at least two hydraulic lines engaged with the hydraulicpressurizer and with each well tool for selectively conveying fluidpressure to each well tool; and a hydraulic controller engaged betweeneach hydraulic line and each well tool, wherein each hydrauliccontroller is operable in response to selective pressurization of one ormore hydraulic lines by the hydraulic pressurizer, and wherein operationof a well tool through the pressurization of one hydraulic linedisplaces fluid which is conveyed through another hydraulic line,wherein the number of hydraulic lines engaged with the hydraulicpressurizer and with each well tool is equal to the number of well toolslocated downhole in the wellbore.
 23. A system for controlling at leastthree well tools located downhole in a wellbore, comprising: a hydraulicpressurizer for selectively pressurizing a fluid, wherein the hydraulicpressurizer is capable of reducing hydraulic pressure for thepressurized fluid below a selected pressure; at least two hydrauliclines engaged with the hydraulic pressurizer and with each well tool forselectively conveying fluid pressure to each well tool; and a hydrauliccontroller engaged between each hydraulic line and each well tool,wherein each hydraulic controller is operable in response to selectivepressurization of one or more hydraulic lines by the hydraulicpressurizer, wherein operation of a well tool through the pressurizationof one hydraulic line displaces fluid which is conveyed through anotherhydraulic line, and wherein each hydraulic controller is capable ofpreventing further movement of the corresponding tool following pressurereduction by the hydraulic pressurizer of the pressurized fluid, atleast one of the hydraulic lines used to provide fluid pressure toactuate one of the at least three well tools is the same as at least oneof the hydraulic lines used to operate the hydraulic controllerassociated with the one of the at least three well tools.